1. 1 Software Engineering: A Practitioner’s Approach, 6/e Chapter 27 Change Management Software Engineering: A Practitioner’s Approach, 6/e Chapter 27 Change Management copyright © 1996, 2001, 2005 R.S. Pressman & Associates, Inc. For University Use Only May be reproduced ONLY for student use at the university level when used in conjunction with Software Engineering: A Practitioner's Approach. Any other reproduction or use is expressly prohibited.

2. 2 The “First Law” No matter where you are in the system life cycle, the system will change, and the desire to change it will persist throughout the life cycle. Bersoff, et al, 1980

3. 3 Software Configuration Management, SCM Identify change Identify change Control change Control change Ensure that change is being properly implemented Ensure that change is being properly implemented Report changes to others who may have an interest Report changes to others who may have an interest

4. 4 What Are These Changes? data otherdocuments code Test Project Plan changes in technical requirements changes in business requirements changes in user requirements software models

5. 5 The Software Configuration programs documents data The pieces Also include software tools, such as editor, compiler, browser and so on.

6. 6 Baselines The IEEE (IEEE Std. No. 610.12-1990) defines a baseline as: The IEEE (IEEE Std. No. 610.12-1990) defines a baseline as: A specification or product that has been formally reviewed and agreed upon, that thereafter serves as the basis for further development, and that can be changed only through formal change control procedures. A specification or product that has been formally reviewed and agreed upon, that thereafter serves as the basis for further development, and that can be changed only through formal change control procedures. a baseline is a milestone in the development of software that is marked by the delivery of one or more software configuration items and the approval of these Software Configuration Items (SCIs) that is obtained through a formal technical review a baseline is a milestone in the development of software that is marked by the delivery of one or more software configuration items and the approval of these Software Configuration Items (SCIs) that is obtained through a formal technical review

7. 7 Baselines Figure 27.1

8. 8 Software Configuration Objects Figure 27.2

9. 9 SCM Repository The SCM repository is the set of mechanisms and data structures that allow a software team to manage change in an effective manner The repository performs or precipitates the following functions [FOR89]: Data integrity Information sharing Tool integration Data integration Methodology enforcement Document standardization

10. 10 Repository Content Figure 27.3

11. 11 Repository Features Versioning. saves all of these versions to enable effective management of product releases and to permit developers to go back to previous versions Dependency tracking and change management. The repository manages a wide variety of relationships among the data elements stored in it. Requirements tracing. Provides the ability to track all the design and construction components and deliverables that result from a specific requirement specification Configuration management. Keeps track of a series of configurations representing specific project milestones or production releases. Version management provides the needed versions, and link management keeps track of interdependencies. Audit trails. Audit trails. establishes additional information about when, why, and by whom changes are made. establishes additional information about when, why, and by whom changes are made.

12. 12 SCM Elements Component elements—a set of tools coupled within a file management system (e.g., a database) that enables access to and management of each software configuration item. Component elements—a set of tools coupled within a file management system (e.g., a database) that enables access to and management of each software configuration item. Process elements—a collection of procedures and tasks that define an effective approach to change management (and related activities) for all constituencies involved in the management, engineering and use of computer software. Process elements—a collection of procedures and tasks that define an effective approach to change management (and related activities) for all constituencies involved in the management, engineering and use of computer software. Construction elements—a set of tools that automate the construction of software by ensuring that the proper set of validated components (i.e., the correct version) have been assembled. Construction elements—a set of tools that automate the construction of software by ensuring that the proper set of validated components (i.e., the correct version) have been assembled. Human elements—to implement effective SCM, the software team uses a set of tools and process features (encompassing other CM elements) Human elements—to implement effective SCM, the software team uses a set of tools and process features (encompassing other CM elements)

13. 13 The SCM Process How does a software team identify the discrete elements of a software configuration? How does a software team identify the discrete elements of a software configuration? How does an organization manage the many existing versions of a program (and its documentation) in a manner that will enable change to be accommodated efficiently? How does an organization manage the many existing versions of a program (and its documentation) in a manner that will enable change to be accommodated efficiently? How does an organization control changes before and after software is released to a customer? How does an organization control changes before and after software is released to a customer? Who has responsibility for approving and ranking changes? Who has responsibility for approving and ranking changes? How can we ensure that changes have been made properly? How can we ensure that changes have been made properly? What mechanism is used to appraise others of changes that are made? What mechanism is used to appraise others of changes that are made? Addresses the following questions …

14. 14 The SCM Process

15. 15 Version Control Version control combines procedures and tools to manage different versions of configuration objects that are created during the software process A version control system implements or is directly integrated with four major capabilities: A version control system implements or is directly integrated with four major capabilities: a project database (repository) that stores all relevant configuration objects a project database (repository) that stores all relevant configuration objects a version management capability that stores all versions of a configuration object (or enables any version to be constructed using differences from past versions); a version management capability that stores all versions of a configuration object (or enables any version to be constructed using differences from past versions); a make facility that enables the software engineer to collect all relevant configuration objects and construct a specific version of the software. a make facility that enables the software engineer to collect all relevant configuration objects and construct a specific version of the software. an issues tracking (also called bug tracking) capability that enables the team to record and track the status of all outstanding issues associated with each configuration object. an issues tracking (also called bug tracking) capability that enables the team to record and track the status of all outstanding issues associated with each configuration object.

16. 16 Change Control STOP

17. 17 Change Control Process—I change request from user developer evaluates change report is generated change control authority decides request is queued for action change request is denied user is informed need for change is recognized change control process—II

18. 18 Change Control Process-II assign people to SCIs check-out SCIs make the change review/audit the change establish a “baseline” for testing change control process—III

19. 19 Change Control Process-III perform SQA and testing activities promote SCI for inclusion in next release rebuild appropriate version review/audit the change include all changes in release check-in the changed SCIs

20. 20 Auditing SCIs ChangeRequests SQAPlan SCM Audit

21. 21 Status Accounting SCIs ChangeRequests ChangeReports ECOs Reporting Engineering Change Order, ECO, for each approved change

22. 22 SCM for Web Engineering-I Content. A typical WebApp contains a vast array of content—text, graphics, applets, scripts, audio/video files, forms, active page elements, tables, streaming data, and many others. The challenge is to organize this set of content into a rational set of configuration objects (Section 27.1.4) and then establish appropriate configuration control mechanisms for these objects. People. Because a significant percentage of WebApp development continues to be conducted in an ad hoc manner, any person involved in the WebApp can (and often does) create content.

23. 23 SCM for Web Engineering-II Scalability. Scalability. As size and complexity grow, small changes can have far-reaching and unintended affects that can be problematic. Therefore, the rigor of configuration control mechanisms should be directly proportional to application scale. As size and complexity grow, small changes can have far-reaching and unintended affects that can be problematic. Therefore, the rigor of configuration control mechanisms should be directly proportional to application scale. Politics. Politics. Who ‘owns’ a WebApp? Who ‘owns’ a WebApp? Who assumes responsibility for the accuracy of the information on the Web site? Who assumes responsibility for the accuracy of the information on the Web site? Who assures that quality control processes have been followed before information is published to the site? Who assures that quality control processes have been followed before information is published to the site? Who is responsible for making changes? Who is responsible for making changes? Who assumes the cost of change? Who assumes the cost of change?

24. 24 Content Management-I The collection subsystem encompasses all actions required to create and/or acquire content, and the technical functions that are necessary to The collection subsystem encompasses all actions required to create and/or acquire content, and the technical functions that are necessary to convert content into a form that can be represented by a mark-up language (e.g., HTML, XML convert content into a form that can be represented by a mark-up language (e.g., HTML, XML organize content into packets that can be displayed effectively on the client-side. organize content into packets that can be displayed effectively on the client-side. The management subsystem implements a repository that encompasses the following elements: The management subsystem implements a repository that encompasses the following elements: Content database—the information structure that has been established to store all content objects Content database—the information structure that has been established to store all content objects Database capabilities—functions that enable the CMS to search for specific content objects (or categories of objects), store and retrieve objects, and manage the file structure that has been established for the content Database capabilities—functions that enable the CMS to search for specific content objects (or categories of objects), store and retrieve objects, and manage the file structure that has been established for the content Configuration management functions—the functional elements and associated workflow that support content object identification, version control, change management, change auditing, and reporting. Configuration management functions—the functional elements and associated workflow that support content object identification, version control, change management, change auditing, and reporting.

25. 25 Content Management-II The publishing subsystem extracts from the repository, converts it to a form that is amenable to publication, and formats it so that it can be transmitted to client-side browsers. The publishing subsystem accomplishes these tasks using a series of templates. The publishing subsystem extracts from the repository, converts it to a form that is amenable to publication, and formats it so that it can be transmitted to client-side browsers. The publishing subsystem accomplishes these tasks using a series of templates. Each template is a function that builds a publication using one of three different components [BOI02]: Each template is a function that builds a publication using one of three different components [BOI02]: Static elements—text, graphics, media, and scripts that require no further processing are transmitted directly to the client-side Static elements—text, graphics, media, and scripts that require no further processing are transmitted directly to the client-side Publication services—function calls to specific retrieval and formatting services that personalize content (using predefined rules), perform data conversion, and build appropriate navigation links. Publication services—function calls to specific retrieval and formatting services that personalize content (using predefined rules), perform data conversion, and build appropriate navigation links. External services—provide access to external corporate information infrastructure such as enterprise data or “back-room” applications. External services—provide access to external corporate information infrastructure such as enterprise data or “back-room” applications.

26. 26 Content Management

27. 27 Change Management for WebApps-I

28. 28 Change Management for WebApps-II